Nanocarbons represented by fullerenes, carbon nanotubes and carbon nanohorns are expected and noted to apply to electronic materials, electrode materials, catalysts and biomaterials.
In recent years, the present inventors have developed fullerene derivatives capable of arbitrarily producing various dimensional nano-mesoscopic materials, and succeeded to construct a fullerene nanowire one-dimensionally organized on molecular level (see, for example, Patent Documents 1 and 2).
The conventionally known nanocarbons such as fullerene derivatives described in Patent Documents 1 and 2 are generally synthesized in a state that molecules are aggregated. The nanocarbons are extremely lightweight material and aggregated during stirring even though mixed with a resin, thus its handling being troublesome. Furthermore, nanocarbons are highly hydrophobic, and therefore are insoluble in polar solvents such as water, thus requiring technology for holding nanocarbons in a stably dispersed state. Moreover, nanocarbons are desirably formed into a state that even primary particles are dispersed in order to exhibit characteristics inherent in nanocarbons.
There is the technology of dispersing fullerene in water (see, for example, Patent Document 3). Patent Document 3 enables a fullerene aqueous dispersion in which fullerene is dispersed in water by using a compound having a hydrophilic group and a hydrophobic group as a dispersant of fullerene.
However, according to the technology described in Patent Document 3, it is still difficult to obtain a stabilized dispersion of high concentration in order to effectively exhibit the function of the fullerene itself.
On the other hand, synthesis of liquid (or viscous) fullerene, not dispersing fullerene in a polar solvent, is recently reported (see, for example, Non-Patent Document 1). However, fullerene described in Non-Patent Document 1 has many substituents on the fullerene core, and the function of fullerene itself is likely disturbed by such many substituents.    Patent Document 1: Japanese Patent Application No. 2005-332390    Patent Document 2: Japanese Patent Application No. 2006-125059    Patent Document 3: JP-A-2004-267972    Non-Patent Document 1: Hirsch et al., Angew. Chem. Int., Ed. 39, 1845 (2000)